Continuous integration is the name of game nowadays for any serious software project. If don't know what I am talking about, you should definitely check out right now
you always wanted to lose some of the clutter on this desktop of yours with the added value of being able to use the same app from any computer ? Meebo is another promising example of the AJAX wave providing a nice IM frontend.
Sun's always been big on sharing and opening, but now more than ever. And now, with the new CEO living and breathing open-source ('til late at night) the policy is more serious than ever.